This invention relates to filter bags, and more particularly, to an improved coupling arrangement for interconnecting the filter bag to a socket of a cooperating member, as well as to another section of a filter bag.
Filter bags are utilized in numerous industrial applications such as for the separating of gases, fluids, etc. In such typical apparatus, a tubular filter bag is employed and is interconnected at its opposite ends to sockets contained in the apparatus. For example, in a gas separation apparatus there is provided a housing with various gas chambers separated by apertured plates. A plurality of filter bags are interconnected in a parallel arrangement between two of these plates extending through one of the gas treating chambers. The gas enters into the gas treating chamber containing the filter bags, is drawn through the tubular filter material of the filter bag, and passes downward through the inside of the filter bag to the next lower chamber where it is drawn off as the output gas.
In this, as well as other types of filtering apparatus, it is necessary to replace the filter bags as they become dirty and clogged. Coupling means must therefore be provided to easily remove an old bag and replace it with a clean filter bag without excessive time, energy or expense. At the same time, while connected to the apertured plate, a fast seal must be provided to prevent leakage of the gas from the coupling means.
Various coupling arrangements have been provided to satisfy the requirements of both providing a secure interconnection, as well as easy replaceability. One such coupling arrangement is described in U.S. Patent No. 3,747,305 issued to O'Dell et al. on July 24, 1973. This patent describes the use of a flat resilient band having a soft resilient collar surroundingly engaging the outer face of the band. The collar has its ends folded upon itself to provide a cross sectional channel-like configuration with ridges at its outer edges and a groove therebetween. The band and collar assembly is interconnected at both ends of the filter bag. The diameters of the band and collar assembly are arranged with relation to the opening in the apertured plate so that the opening will snugly fit in the groove in the center of the channel-like configuration. The folded over sections of the collar provide holding ridges for securing the filter bag against the opening. However, since the opening will snugly fit in the groove of the collar, the outer and thicker ridges must be able to be easily compressed as the filter bag is inserted into or removed from the opening.
The aforedescribed coupling arrangement results in a most difficult manufacturing operation. The edges of the collar must be folded over onto itself and then secured, such as by sewing onto the main body of the collar. A single such fold may not be sufficient to provide enough retaining hold on the opening wall and it may be necessary to have at least two or more folded over sections of material. This results in a conflicting situation; the increased thickness at the edges of the collar material provides increased holding of the filter bag in the opening, but will also make insertion and removal of the bag into the opening more difficult and the cost of manufacture greater. As a result, the aforedescribed coupling arrangement becomes an expensive arrangement, difficult to manufacture and also provides difficulty in practical usage.
An additional problem with the aforementioned filter bag is that the identical coupling arrangement is provided at both ends of the bag so that either end can be inserted into an aperture plate. However, it has been found that a filter bag is not worn out uniformly. For example, the bottom portion of the bag may be worn out or become dirty faster than the upper portion. Thus, while the upper portion can still be used, the bottom portion must be replaced. However, in the aforementioned patent, when even a part of the filter bag becomes dirty or worn, the entire filter bag in the chamber must be replaced.